Treatment of chemical and particulate laden exhaust fume gasses is a major concern in the protection of the environment. Various forms of air and gas cleaners or scrubbers are known in the prior art including scrubbers for removing particulate solids from a contaminated air stream. Most of these prior art devices, while in general accomplishing their objectives, are unduly complex and bulky and tend to be inefficient and costly.
Treatment of an air stream by impinging the air stream on a scrubbing liquid is well known in the art as illustrated by U.S. Pat. No. 3,624,696 entitled "Gas Scrubbing Apparatus" issued Nov. 30, 1971 to Cohen et al. Cohen et al. discloses a gas scrubber where gas enters in a downward direction on one side of the scrubber and impinges on a scrubbing liquid. The gas then reverses direction and flows upward through a pair of baffles which reverse the direction of the gas. The gas then flows through a mist eliminator before passing through a blower and being exhausted. One limitation of the device of Cohen et al. is that the gas enters the side of the scrubber moving in a downward direction. If a scrubber is to be used for cleaning air from a vent hood, such as might be placed over a work area, the gasses are typically exhausted upward out of the hood and must first be reversed before entering the scrubbing device of Cohen et al. During this first reversal, many particulates are removed from the gas and either fall back into the vent hood or are left in the duct system.
U.S. Pat. No. 3,673,769 entitled "Gas Scrubber", issued Jul. 4, 1972 to Gleason describes a device similar to the Cohen et al. device wherein gas enters the side of the scrubber and is immediately turned at a right angle to impinge downward onto a scrubbing liquid in a sump. After passing through the scrubbing liquid, the gas exhausts the sump area through a set of vanes and out through the top of the air scrubber.
U.S. Pat. No. 3,713,277 entitled "Fog Impingement Scrubbing System", issued Jan. 30, 1973 to Sackett shows a system which also has side entry of the air stream followed by diverting the air stream downward as it passes over scrubbing liquid sprayers. The gas then reverses direction at the bottom of the scrubber and flows up through a filtering system and out the top of the scrubber.
U.S. Pat. No. 3,721,068 entitled "Gas Stream Scrubber", issued Mar. 20, 1973 to Vincent describes an air scrubbing device with a side entry port, and a series of baffles causing the gas flow to reverse direction. The baffles may be moved to create a longer or shorter gas flow path, depending upon the gas pressure within the scrubber.
U.S. Pat. No. 3,815,332 entitled "Gas Scrubber and Method", issued Jun. 11, 1974 to Bobrowsky et al. shows a system having the gas stream entering the top of the scrubber and flowing through the scrubbing liquid before exiting back out the top of the scrubber.
U.S. Pat. No. 4,533,522 entitled "Apparatus for the Desulferization of Flue Gasses", issued Aug. 6, 1985 to Leimkuhler shows a system having a plurality of nozzles for dispersing the scrubbing liquid. In this system the gasses enter from the top of the scrubber, reverse direction as they pass near the sump area of the scrubber and exit back out the top of the scrubber.
All the above described art uses at most a single mist eliminator to remove scrubbing liquid droplets from the air stream. Often this leaves the air stream still saturated with water, which can build up in the air ducts following the scrubber. Also, all the above described art provides only a single impingement of the gas on sump containing the scrubbing or cleansing liquid.
There is need in the art then for a gas scrubbing device which allows entry of the gas stream from the bottom of the scrubber and exits through the top of the scrubber to allow the scrubber to conveniently be placed on top of a vent hood. There is further need in the art for such a scrubber containing multiple mist eliminators to more completely dry the gas before it exits the scrubber. A still further need in the art is to direct the contaminated gas toward multiple sumps containing scrubbing liquid to remove the highest amount of particulate matter. The present invention meets these and other needs in the art.